RAID5 Runnig Slow

[Erland]

I'm running

OS: Windows 2k3 Server
MotherBoard: MSI 7145 / RS480M
SATA Card: SYBA SD-SATA2-4IR PCI SATA II Controller Card RAID 0/1/5/10 JBOD - Retail
CPU: AMD Sempron 3300+
RAM: 2GB
Drives: IDE 40GB(OS) / SATA 1.5TB(Storage / SATA 600GB(Backup / Windows-RAID5)

Now I have the OS on a IDE 40GB Maxtor Drive. It runs fine.

I then got the 1.5TB and added it to the on-board SATA Controller.

Later on I got a 320GB and 3x300GB drives all SATA. Well one of the 300GB drives were DOA so now I have a 320GB and 2x300GB all on RAID5. The RAID is setup with Windows. It is not the software that came with the Controller card or HARDWARE RAID.

Instead of putting it on the MOBO controller I decided to put it on my SATA CARD so if and when I upgrade the MOBO I won't have to worry about getting another with the same controller I can just move the SATA card.

I decided not to move the 1.5TB because last time I moved a SATA drive with data to another controller I lost all the data.

Well now when I transfer data to the RAID5 the speeds suck major ass. If I transfer a 6GB file it will take up to 109 Minutes.

If I transfer a 2GB file from the RAID5 to the 1.5TB it takes 45 seconds. So I figure 2/3 minutes max for a 6GB File.

I have:

No Anti Virus installed
I do not have windows indexing turned on
I do not have defrag setup or running.
I do not have anything else accessing the disks that I know of when I ran these tests.

Tests done with HDTune and HDTach. Screen shots for each drive are here.

What gets me is that the RAID5 does not show up as 1 partition but, each individual drive. I was told over at TomsHardware that this shouldn't be. However the people over at TH are starting to worry me because they are insisting that I setup my drive as a RAID0 and put my OS on it even though I'm using to backup data.

I have an external drive that I'm getting ready to setup for external backup. So please don't go on explaining that this is not proper way to backup data. Right now I have a 160GB External Drive due to the actual data that needs to be backed up is less than 160GB it's more like 60-90GB and mostly pictures and documents. I'm interested in the write speed of the RAID5 being so slow not how to properly backup data.

I don't mean to be rude about it but this is the 3rd place I have gone and the other 2 are basically just preaching about it not being a proper way to backup data rather then addressing the issue of the RAID5 being so slow.

I assume it's slow due to it being a "Windows RAID5" and not a "Hardware RAID5" which I do not have the money for. Also Right now I'm waiting on another 300GB to be RMA'ed and I will probably kill the RAID5 and Go with 2x300GB in RAID0 + RAID1 or what I believe is called RAID10.

Please take a look at the screenshot's from HDTune and HDTach.

40GB:
http://vnc.3r14nd.com:8080/ima...Computer/drives/40.JPG
http://vnc.3r14nd.com:8080/ima...mputer/drives/40GB.JPG

1.5TB
http://vnc.3r14nd.com:8080/ima...mputer/drives/1500.JPG
http://vnc.3r14nd.com:8080/ima...uter/drives/1500GB.JPG

320GB
http://vnc.3r14nd.com:8080/ima...omputer/drives/320.JPG
http://vnc.3r14nd.com:8080/ima...puter/drives/320GB.JPG

300GB - 1
http://vnc.3r14nd.com:8080/ima...puter/drives/300-1.JPG
http://vnc.3r14nd.com:8080/ima...ter/drives/300-1GB.JPG

300GB -2
http://vnc.3r14nd.com:8080/ima...puter/drives/300-2.JPG
http://vnc.3r14nd.com:8080/ima...ter/drives/300-2GB.JPG

For some reason my img's are not showing up the way I want them...

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The above does not work here so...links are what you get...

 

[Emulex]

you gotta buy a real raid card to do raid-5 like 512meg of bbwc. even then you have to do so many reads its going to be wicked slow compared to raid-10.

especially with those slow drives.

 

[Erland]

So your telling me that without an actual RAID card that the loss of 50MB/s transfer speed is normal on those 3 drives?

Without the RAID5 implemented their transfer rates will match that of the 1.5TB drive.

 

[betaflame]

That would be because you bought a shitty card. Read the newegg reviews man!

 

[Syntax Error]

You're using a FakeRAID card, that's why.

 

[betaflame]

Solution:
Put the 2x 300 and 1x320 on the Mobo controller and use Windows 2003 software RAID5

 

[Erland]

I'll try that tonight.. see if it gets any better but, unfortunately I doubt it.

I didn't realize getting a card without hardware RAID support will kill the speeds by half. I figured 25% at most but not 50%

 

[betaflame]

I also would wait for the 3rd 300GB to come back from RMA and keep the 320GB out of the RAID. Probably not important though.

Actually you could just yank the 320 and let it regenerate onto the 300GB, so that's nice.

 

[Emulex]

fake raid should be okay with raid-10 but you must understand that when you write a sector you have to read in the data from all drives to recompute the crc to write back out. then you have to wait for all raid-5 drives to finish writing.

this is where cache plays HUGE effect on the extra reads and writes of raid-5.

imo i would just bite the bullet and do raid-10 if you need protection. you'll get the stripe read performance. but keep in mind still without write back cache you have to wait for all drives to write their data stripe out.

i found a p400 with bbwc for $99 on ebay but you can only use them on certain hp workstations. score with 4 fan out cable even.

stripe size is a big thing to consider too. 64kb is good for sql server..

cache plays huge role in read and write because you have to:
* Read the old data block
* Read the old parity block
* Compare the old data block with the write request. For each bit that has flipped (changed from 0 to 1, or from 1 to 0) in the data block, flip the corresponding bit in the parity block
* Write the new data block
* Write the new parity block

 

[Keitero]

FakeRAID 5 as everyone has stated is going to be slow. That being said however, my FakeRAID on a Promise TX4 with 4x 7200.10 320GBs ran fine and sustained about 120MB/s with a burst of 133B/s (PCI bus limit). You can snag a cheap hardware RAID card on ebay for dirt cheap (a Dell Perc seems like a steal at $200-ish). Otherwise, RAID 1 is your best bet for redundancy.

 

[Emulex]

with the price of drives being so little it almost makes sense to do raid-10. honestly the only reason i do raid-6 is because of SATA and that is for backing up (iscsi) vm's. raid-5 is insane if you have too many sata disks you very well might hit the double failure during a lengthy rebuild.

 

[pugh]

As soon as I saw this topic I said to myself he is using crappy on board raid and not a REAL raid card. Then i saw the name Sybex... As the other said get something that is meant to do the job right. When I got into using RAID. I didn't cheap it out. Spent some good cash and got a Areca and 4 drives . I have been happy since.

 

[Erland]

Well I moved them from the SATA card to on-board SATA controller and here are the results.

http://vnc.3r14nd.com:8080/ima...ter/drives/300-1.1.JPG
http://vnc.3r14nd.com:8080/ima...ter/drives/300-2.1.JPG
http://vnc.3r14nd.com:8080/ima...puter/drives/320.1.JPG

So using the SATA card did slow it down but, even the on board is slow so now I'm looking at Windows software RAID5 being the one that's slowing it down now.

I can't wait for the other 300GB to come back so I can put them in RAID10 instead.

 

[Emulex]

dude go buy yourself a real raid card. like a used cerc off ebay for $100 with a bbwc.

i mean for real.

 

[RebateMonger]

I'm not sure why all the comments about "FakeRAID". It sounds like the O.P. is running a RAID 5 array using three dynamic disks and Windows software RAID. He's doing a write test, which is hardly the strong point of any RAID 5 array, especially with no hardware assistance for the parity calculations.

 

[Emulex]

it's not the parity. the cpu can handle that all day long without breaking a sweat, its the double read and double write without a cache that hurts so badly.